Pause the game and then highlight the given choice on the Options menu and enter the following code. When a code is accepted, a confirmation message flashes at the center of the screen, behind the Options menu.

Effect	Code
Acquire all Runes (when touching Rune on map E1L7)	Highlight Customize Controls, then press R, Z, L, X, Y, L, R, Y, L, R.
Acquire all weapons and maximum ammo for each	Highlight Customize Controls, then press R, X, L, Z, L, R, Y, L, R, Y.
Alter Analog controller setup/functions	Highlight Customize Controls, then press R, R, L, X, Y, Z, X, Y, Z.
Begin again on current map, with original status	Highlight Reset To Defaults, then press R, L, X, Y, Z, R, L, X, Y, Z.
Easy difficulty setting	Highlight Music Volume, then press R, L, X, Y, Z, R, L, X, Y, Z.
Hard difficulty setting	Highlight Music Volume, then press R, X, L, Z, L, R, Y, L, R, Y.
Invincibility	Highlight Customize Controls, then press R, L, X, Y, Z, R, L, X, Y, Z.
Nailguns Shoot Tracer	Highlight Auto Targeting, then press R, L, X, Y, Z, R, L, X, Y, Z.
Normal difficulty setting	Highlight Music Volume, then press R, R, L, R, X, Y, Z, X, Y, Z.
Regain full health	Highlight Customize Controls, then press R, Y, L, Y, X, Y, Z, X, Y, Z.
Some player weapons fire enemy ammo type (varies by map)	Highlight Auto Targeting, then press R, R, L, R, X, Y, Z, X, Y, Z.
Toggle player's immunity to gravity on/off	Highlight Lookspring, then press R, R, L, R, X, Y, Z, X, Y, Z.
Toggle use of 5-grenade rocket warheads on/off	Highlight Auto Targeting, then press R, X, L, Z, L, R, Y, L, R, Y.
View map	Highlight Customize Controls, then press L, R, L, R, Z, Y, X, X, Y, Z.
Warp to new map (from START map, or with 4 Runes)	Highlight Reset To Defaults, then press R, R, L, R, X, Y, Z, X, Y, Z.